1. Field of the Invention
The present invention relates to a photosensititve paste and to methods of using the paste for producing fine patterns.
2. Technical Background
Techniques involving the use of photosensitive pastes for forming fine patterns are known in the art. Photosensitive pastes generally include a polymerizable monomer and photopolymerization initiator. Depending on the intended application, photosensitive pastes may also include conductive particles, glass powder, organic binder, organic solvent, and other additives. The photosensitive paste is applied onto a substrate on which a pattern is to be formed, and the paste is exposed to light in the desired pattern. During the exposure process, polymerization progresses in the parts that have been irradiated with light, and the pattern is then formed in a subsequent development process. The pattern is then fired, and a pattern consisting of inorganic material is formed on the substrate. The pattern that has been formed functions as an electrode, conductor, wall, or the like.
Technical progress has been accompanied by demand for the formation of finer patterns. However, when attempts are made to form fine patterns, the patterns are sometimes not properly formed, causing increases in the rate of defects. When electrode patterns are formed, for example, adjacent patterns may not be adequately separated and can cause shorts, which can be a fatal flaw in the final product.
Techniques for forming fine patterns have been developed from a variety of perspectives. Examples include techniques for modifying the structure itself of the electronic device, techniques related to improving the light exposure method, techniques related to improving components in the paste, and so forth. JP2008-39962A, for example, disclosed a technique for forming a resistor layer using a photosensitive paste comprising glass powder, ruthenium oxide powder, and a photosensitive organic component, wherein the mass ratio between the glass powder and ruthenium oxide is 30:70 to 90:10, the central particle diameter of the glass powder is in the range from 0.5 to 5 μm, and the central particle diameter of the ruthenium oxide is in the range from 0.01 to 0.3 μm. JP2005-215134A disclosed a photosensitive inorganic paste composition comprising at least a photopolymerization initiator, photopolymerizable monomer, and inorganic powder, wherein a Norrish type I photopolymerization initiator and a hydrogen abstraction type of photopolymerization initiator are simultaneously included as the photopolymerization initiator. It would be desirable to develop an improved process for fine pattern generation that results in less residue remaining on the substrate and that avoids product defects.